In modern surgery a large number of electronic components and electrical devices are employed to ensure that operations are performed reliably and without harm to the patient. For instance, high-frequency surgery has been used for years, in both human and veterinary medicine, in order to coagulate and/or to cut biological tissue. In this procedure high-frequency current is conducted through the tissue that is to be treated or removed, so that owing to protein coagulation and dehydration the tissue is altered or disintegrates. The tissue thus contracts in such a way that the vessels are closed and bleeding is stanched. A subsequent increase in current density causes an explosive vaporization of the tissue fluid and the cell membranes are torn apart, so that the tissue is completely transected. Methods of this kind, as opposed to a purely mechanical cutting procedure, offer the advantage of haemostasis at the cut edges.
In principle both the coagulation and the cutting can be performed with the same medical instrument. In both modes of operation the instrument is supplied with high-frequency voltage from a high-frequency generator. To control the high-frequency generator a large number of parameters are required, and these must be chosen according to which of the two operation modes is intended, the nature of the tissue and other criteria in order to achieve an optimal result of the coagulation or cutting. Modern instruments provide a large number of modes that assemble the parameters needed for a particular application scenario. In practice it has turned out that during an operation a frequent alternation between a particular coagulation mode and a particular cutting mode is necessary, whereas it is less common for a change to be made between different cutting modes or different coagulation modes as such. To satisfy the latter requirement as well, the applicant provides instruments for coagulating and cutting biological tissue which are constructed so that two buttons on the handle of the instruments can be used to switch directly between a preset coagulation mode and a preset cutting mode, while a third button on the handle enables suitable modes to be selected for the first and the second button. A disadvantage of this three-button handle resides in the fact that in order to operate the buttons reliably, the handle must be securely gripped. Furthermore, it requires considerable time for a user to become accustomed to “blind” operation of the three keys, because of the need to change continually between different finger positions. It can also happen that due to the actuation of the wrong button, or several buttons at once, the device is erroneously controlled, which sometimes can have very negative effects on the course of the operation.
It is the objective of the present invention to develop a surgical device of the kind cited at the outset further, in such a way that switching between and executing a plurality of modes for controlling the surgical device is ensured, by simple and reliable means.